Tricolor exposure ratios

[KB Photo]

Hello,
I want to try exposing B&W pan film using a tricolor filter set (#25R, #58G, #47B). What exposure ratios (R:G:B) are a good starting point for photos outside in daylight?

 

[rmolson]

tri color ratios

Generally you should be able to use the published filter factors to establish exposure. If you are planning on doing any kind of 3 color printing, dye transfer etc. the contrast of each film ( called printers ) much match. Otherwise you may encounter what is called cross over. Where the curves do not match and literally cross over at different points on the straight line making it near to impossible to have neutral highlights and mid tones.

 

[richard ide]

IIRC the blue separation negative will be much lower contrast unless you extend development time. I would recommend that you make test exposures including a 20 step reflection gray scale. adjust exposure/development until you have the same density range on each negative. It has been 30 years since I did this so I won't guess what adjustments to make. You may be able to find exact information on the net. I would imagine the ratios would be similar to those used for making dye transfer pan matrix films.

 

[KB Photo]

Thanks,
Your suggestions are good and I should have thought of them. When the exposure and contrast of the seperations are correct, the density of the steps should appear the same. Of course, it will be necessary to photograph the steps with the same lighting (color temp) as the final scene.